Magneto-resistive element, magnetic head employing it, magnetic recording apparatus, and magnetic memory

ABSTRACT

The present application provides a magneto-resistive element excellent in symmetry of playback waveforms. The basic construction of the present application is as follows. That is, a magnetic layer  13 , an insulating layer  14 , and a magnetic layer  15  are laminated; a power supply  18  for applying a voltage between two magnetic layers is provided; an anti-ferromagnetic layer  16  is laminated on the magnetic layer  15 , direction of which magnetization is substantially parallel or counter-parallel with a detecting direction of an external magnetic field, and when the external magnetic field is not present, a power supply  17  for causing a current to flow in a non-magnetic metal layer  12  and in an inner direction of a layer surface thereof is provided so that a direction of magnetization of the magnetic layer  13  is substantially at right angles to the detecting direction of the external magnetic field; and there is provided a signal detector  19  for detecting a change of current tunneling through an insulating layer when the direction of magnetization of the magnetic layer  13  is changed by the external magnetic field.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a magneto-resistive element usedfor a magnetic head, a magnetic field sensor or the like, a magnetichead using the magneto-resistive element, a magnetic recording apparatus(magnetic recording and playback apparatus), and a magnetic memory.

[0003] 2. Description of the Related Art

[0004] A multi-layer indicating a magnetic tunneling phenomenon isreported in Physics Letters, vol. 54A (1975), No. 3, p. 225 by Julia.With higher density of magnetic recording, as a future playback magnetichead, application of the multi-layer to a magneto-resistive type headhas been studied.

[0005] The multi-layer comprises a laminate having a magnetic layer, aninsulating layer, and a magnetic layer laminated in the order, and whenan electron issued from one magnetic layer and tunneling through theinsulating layer enters the other magnetic layer, a change occurs in thetunneling probability depending on the direction of magnetization of twomagnetic layers. The change in the tunneling probability is observed asa magneto-resistance.

[0006] Where the conventional multi-layer is used for themagneto-resistive element, it is necessary, when an external magneticfield is not present, to make the direction of magnetization of amagnetic layer magnetized and rotated by the external magnetic fieldsubstantially at right angles to the detecting direction of the externalmagnetic field. This is necessary for the reason that symmetry ofplayback outputs when the magneto-resistive element is applied to theexternal magnetic field is better. However, a leakage magnetic fieldfrom the other magnetic layer is applied to the magnetic layermagnetized and rotated by the external magnetic field, and the directionof magnetization is not at right angles to the detecting direction ofthe external magnetic field. The leakage magnetic field from the othermagnetic layer delicately changes due to the construction of themagneto-resistive element, the thickness of the magenta layer, theunevenness of the insulating layer, and so on, thus posing a problemthat controlling the direction of magnetization of the magnetic layer isdifficult.

[0007] It is a first object to provide a magneto-resistive element whichis excellent in symmetry of playback waveforms.

[0008] It is a second object of the present invention to provide amagnetic head using such a magneto-resistive element as described.

[0009] It is a third object of the present invention to provide amagnetic recording apparatus using such a magnetic head as described.

[0010] It is a fourth object to provide a magnetic memory which isexcellent in symmetry of playback waveforms.

SUMMARY OF THE INVENTION

[0011] For achieving the aforementioned first object, according to thepresent invention, there is provided a magneto-resistive elementcomprising, a multi-layer having a first magnetic layer, an insulatinglayer, and a second magnetic layer laminated on a substrate in saidorder, a means for applying a voltage between the first magnetic layerand the second magnetic layer, a direction of magnetization of onemagnetic layer of the first magnetic layer and the second magnetic layerbeing substantially parallel or counter-parallel with a detectingdirection of an external magnetic field, a control means for making adirection of magnetization of the other magnetic layer of the firstmagnetic layer and the second magnetic layer substantially at rightangles to the detecting direction of an external magnetic field when theexternal magnetic field is not present, and a means for detecting, whenthe direction of magnetization of the other magnetic layer is changed bythe external magnetic field, a change of a current tunneling through theinsulating layer caused thereby.

[0012] In the magnetic resistive element, if the direction ofmagnetization of the other magnetic layer is made completely at rightangles to the detecting direction of the external magnetic field,playback waveforms are symmetrical, but if deviated from the rightangles, the symmetry lowers. The substantially right angles termedherein means that if the non-symmetry of playback waveforms is in therange within 5%, the direction may be deviated from the right angles.This deviation is for example, approximately ±5 depending on the shapeof the playback waveform.

[0013] Further, the terms “a direction of magnetization of one magneticlayer being substantially parallel or counter-parallel with a detectingdirection of an external magnetic field” herein means that a deviationin the range similar to the direction of magnetization of the othermagnetic layer is allowed to be parallel or counter-parallel. The sameis true for the following description.

[0014] In the electro-resistive element, an anti-ferromagnetic layer islaminated on one magnetic layer, and the anti-ferromagnetic layer andone magnetic layer are subjected to magnetic exchange coupling to makethe direction of magnetization of one magnetic layer substantiallyparallel or counter-parallel with the detecting direction of theexternal magnetic field.

[0015] In this case, as the control means, there can be provided a meansfor causing a current to flow in an inner direction of a layer surfaceof at least one layer of the anti-ferromagnetic layer and a crystalorientation control layer. Further, as the control means, there can beprovided a means for causing a current to flow in an inner direction ofa layer surface of the other magnetic layer, and a means for causing acurrent to flow in an inner direction of a layer surface of anon-magnetic metal layer laminated on a multi-layer.

[0016] Further, coercive force of one magnetic layer is made higher thanthat of the other magnetic layer, without providing theanti-ferromagnetic layer, and as the control means, there can beprovided a means for causing a current to flow in an inner direction ofa layer surface of a nonmagnetic metal layer laminated on a multi-layer.Further, likewise, coercive force of one magnetic layer is made higherthan that of the other magnetic layer, being arranged on a substrate andthere is provided with a means for causing a current to flow in an innerdirection of a layer surface of one magnetic layer.

[0017] Further, for achieving the aforementioned first object, accordingto the present invention, there is provided a magneto-resistive elementcomprising, a multi-layer having a first magnetic layer, a firstinsulating layer, a second magnetic layer, a second insulating layer,and a third magnetic layer laminated on a substrate in said order, ameans for applying a voltage between the first magnetic layer and thethird magnetic layer, a direction of magnetization of one magnetic layerof a set of the first and third magnetic layers and the second magneticlayer being substantially parallel or counter-parallel with a detectingdirection of an external magnetic field, a control means for making adirection of magnetization of the other magnetic layer of the set of thefirst and third magnetic layers and the second magnetic layersubstantially at right angles to the detecting direction of the externalmagnetic field when the external magnetic field is not present, and ameans for detecting, when the direction of magnetization of the othermagnetic layer is changed by the external magnetic field, a change of acurrent tunneling through the insulating layer caused thereby.

[0018] As the control means, there can be provided a means for makingcoercive force of one magnetic layer higher than that of the othermagnetic layer, laminating a non-magnetic metal layer on a multi-layer,and causing a current to flow in an inner direction of a layer surfaceof the non-magnetic metal layer.

[0019] Further, anti-ferromagnetic layers are provided on both sides ofa multi-layer, one magnetic layer comprising a set of the first andthird magnetic layer, and as the control means, there can be provided ameans for causing a current to flow in an inner direction of a layersurface of at least one layer of the anti-ferromagnetic layer and acrystal orientation control layer laminated on the side opposite to onthe side in which a multi-layer of one of the anti-ferromagnetic layersis arranged.

[0020] Further, for achieving the aforementioned first object, accordingto the present invention, there is provided a magneto-resistive elementcomprising, a multi-layer having a hard magnetic layer, a non-magneticmetal layer, a first soft magnetic layer, an insulating layer, a secondsoft magnetic layer, and an anti-ferro magnetic layer laminated on asubstrate in said order from the side closer to the substrate, a meansfor applying a voltage between the first soft magnetic layer and thesecond magnetic layer, the anti-ferromagnetic layer and the second softmagnetic layer being subjected to magnetic exchange coupling, adirection of magnetization of the second soft magnetic layer beingsubstantially parallel or counter-parallel with a detecting direction ofan external magnetic field by the exchange coupling, and a direction ofmagnetization of the first soft magnetic layer being made substantiallyat right angles to the detecting direction of an external magnetic fieldwhen the external magnetic field is not present, and a means fordetecting, when the direction of magnetization of the first softmagnetic layer is changed by the external magnetic field, a change of acurrent tunneling through the insulating layer caused thereby.

[0021] Further, for achieving the aforementioned second object,according to the present invention, there is provided a magnetic headcomprising a magneto-resistive type head for read, and an induction typehead for write, the magneto-resistive element described in any one ofthe foregoing being used as the magneto-resistive type head.

[0022] Further, for achieving the aforementioned third object, accordingto the present invention, there is provided a magnetic recordingapparatus comprising a magnetic recording medium, a magnetic headprovided in correspondence with a recording surface of the magneticrecording medium, a driving unit for a magnetic recording medium, adriving unit for a magnetic head, and a recording and playback signalprocessing system, the afore-mentioned magnetic head (in the secondobject) being used as said magnetic head.

[0023] Further, for achieving the aforementioned third object, accordingto the present invention, there is provided a magnetic memory comprisinga magneto-resistive element according to Embodiments 1, 2, 3 or 4described later of the aforementioned magneto-resistive elements, and amagnetic field generating mechanism for directing a direction ofmagnetization of one magnetic layer at the desired direction. Themagnetic memory may be provided with a means for heating amagneto-resistive element.

[0024] As described above, according to the present invention, amagneto-resistive element using a multi-layer in which two or threemagnetic layers are separated by an insulating layer is used, aninduction magnetic field is applied to a rotating magnetic layermagnetized by an external magnetic field, and the induction magneticfield applied to the magnetic layer is offset by a leakage magneticfield from a magnetic layer with magnetization fixed, as a result ofwhich the magnetization of the magnetic layer is substantially at rightangles to the magnetic field applying direction to thereby provide anexcellent symmetry of playback waveforms.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025]FIG. 1 is a sectional construction view of a magneto-resistiveelement according to Embodiment 1 of the present invention;

[0026]FIGS. 2A to 2C are schematic views for explaining the operatingprinciple of a magneto-resistive element according to Embodiment 1 ofthe present invention;

[0027]FIG. 3 is a view showing a relationship between an externalmagnetic field and a tunnel current in the magneto-resistive elementaccording to the present invention;

[0028]FIG. 4 is a view showing an applied magnetic field and a playbackwaveform in the magneto-resistive elements of the present invention andthe prior art;

[0029]FIG. 5 is a sectional construction view of a magneto-resistiveelement according to Embodiment 2 of the present invention;

[0030]FIG. 6 is a sectional construction view of a magneto-resistiveelement according to Embodiment 3 of the present invention;

[0031]FIGS. 7A and 7B are respectively a plan view and a sectional viewof a magnetic disk according to one embodiment of the present invention;

[0032]FIGS. 8A to 8B are schematic views for explaining the operatingprinciple of a magnetic memory according to one embodiment of thepresent invention.

[0033]FIG. 9 is a schematic view for explaining the schematicconstruction of a magnetic memory according to one embodiment of thepresent invention;

[0034]FIG. 10 is a sectional construction view of a magneto-resistiveelement according to Embodiment 5 of the present invention;

[0035]FIGS. 11A to 11C are schematic views for explaining the operatingprinciple of a magneto-resistive element according to Embodiment 5 ofthe present invention; and

[0036]FIG. 12 is a view showing a relationship between an externalmagnetic field and a tunnel current in the magneto-resistive elementaccording to the present invention.

[0037]FIG. 13 is a sectional construction view of a magneto-resistiveelement according to Embodiment 4 of the present invention.

[0038]FIG. 14 is a sectional construction view of a magneto-resistiveelement according to Embodiment 4 of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0039] Before explaining some concrete embodiments, some useful modes ofthe invention are showed as follows:

[0040] The first mode of the present invention is a magnetic head havinga magneto-resistive element, said magneto-resistive element comprising:a substrate, a multi-layer having at least a first magnetic layer, aninsulating layer, and a second magnetic layer laminated on saidsubstrate, a voltage supplier applying a voltage between the firstmagnetic layer and the second magnetic layer; a direction ofmagnetization of one magnetic layer selected from a group of the firstand the second magnetic layers being substantially parallel orcounter-parallel with a detecting direction of an external magneticfield; a direction of magnetization of the other magnetic layer, whichis not substantially parallel or counter-parallel with the detectingdirection of the external magnetic field, being changeable by saidexternal magnetic field, a controller being a controller causing acurrent to flow in at least one conductive layer selected from a groupof layers laminated on said substrate in a direction crossing alaminating direction of said multi-layer and perpendicular to theexternal magnetic field; the controller being for making a direction ofmagnetization of the other magnetic layer, which is changeable by saidexternal magnetic field, substantially perpendicular to the detectingdirection of the external magnetic field when the external magneticfield is not present, and a detector detecting, when the direction ofmagnetization of the other magnetic layer is changed by the externalmagnetic field, a change of current tunneling through the insulatinglayer caused thereby.

[0041] Typical measures for making a direction of magnetization of onemagnetic layer selected from the first and the second magnetic layerssubstantially parallel or counter parallel with a detecting direction ofan external magnetic field are as follows:

[0042] As stated before, at first, one is an anti-ferromagnetic layerformed adjacent to a magnetic layer of the multi-layer. Theanti-magnetic ferromagnetic layer and the magnetic layer are subjectedto magnetic exchange coupling to make the direction of magnetization ofthe magnetic layer substantially parallel or counter-parallel with thedetecting direction of the external magnetic field.

[0043] The second, it is to make coercive force of one magnetic layer ofthe multi-layer higher than coercive force of the other magnetic layerof the multi-layer.

[0044] Therefore, the second mode of this invention is a magnetic headhaving a magneto-resistive element, said magneto-resistive elementcomprising: a substrate, a multi-layer having at least a first magneticlayer, an insulating layer, and a second magnetic layer laminated onsaid substrate, an anti-ferromagnetic layer being formed on lower orupper of said multi-layer, a voltage supplier applying a voltage betweenthe first magnetic layer and the second magnetic layer; a direction ofmagnetization of one magnetic layer selected from a group of the firstand the second magnetic layers being substantially parallel orcounter-parallel with a detecting direction of an external magneticfield; a direction of magnetization of the other magnetic layer, whichis not substantially parallel or counter-parallel with the detectingdirection of the external magnetic field, being changeable by saidexternal magnetic field, a controller being a controller causing-acurrent to flow in at least one conductive layer selected from a groupof layers laminated on said substrate in a direction crossing alaminating direction of said multi-layer and perpendicular to theexternal magnetic field; the controller being for making a direction ofmagnetization of the other magnetic layer, which is changeable by saidexternal magnetic field, substantially perpendicular to the detectingdirection of the external magnetic field when the external magneticfield is not present, and a detector detecting, when the direction ofmagnetization of the other magnetic layer is changed by the externalmagnetic field, a change of current tunneling through the insulatinglayer caused thereby.

[0045] The anti-ferromagnetic layer is able to be formed on saidsubstrate, and at that time the multi-layer is formed on theanti-ferromagnetic layer. Moreover the multi-layer is also able to beformed on the substrate, and at this time the anti-ferromagnetic layeris formed on the multi-layer.

[0046] The third, a magnetic head having a magneto-resistive element,said magneto-resistive element comprising: a substrate, a multi-layerhaving at least a first magnetic layer, an insulating layer, and asecond magnetic layer laminated on said substrate, coercive force of onemagnetic layer selected from a group of the first magnetic layer and thesecond magnetic layer being higher than coercive force of the othermagnetic layer selected from the group of the first magnetic layer andthe second magnetic layer, a voltage supplier applying a voltage betweenthe first magnetic layer and the second magnetic layer; a direction ofmagnetization of one magnetic layer selected from a group of the firstand the second magnetic layers being substantially parallel orcounter-parallel with a detecting direction of an external magneticfield; a direction of magnetization of the other magnetic layer, whichis not substantially parallel or counter-parallel with the detectingdirection of the external magnetic field, being changeable by saidexternal magnetic field, a controller being a controller causing acurrent to flow in at least one conductive layer selected from a groupof layers laminated on said substrate in a direction crossing alaminating direction of said multi-layer and perpendicular to theexternal magnetic field; the controller being for making a direction ofmagnetization of the other magnetic layer, which is changeable by saidexternal magnetic field, substantially perpendicular to the detectingdirection of the external magnetic field when the external magneticfield is not present, and a detector detecting, when the direction ofmagnetization of the other magnetic layer is changed by the externalmagnetic field, a change of current tunneling through the insulatinglayer caused thereby.

[0047] Coercive force of either of (or any one of) the magnetic layersof the multi-layer is able to be higher than that of the other magneticlayer.

[0048] The controller is a controller causing a current to flow in atleast one conductive layer selected from a group of layers laminated onsaid substrate in a direction crossing a laminating direction of saidmulti-layer. In other words, the current flows in a direction of thelaminated layer surface. The direction of the current of the controllercrosses a direction of tunnel current tunneling through the insulatinglayer.

[0049] And the controller is also for making a direction ofmagnetization of the other magnetic layer, which is changeable by saidexternal magnetic field, substantially perpendicular to the detectingdirection of the external magnetic field.

[0050] At least the conductive layer to flow the current is able to beemployed from a group of several conductive layers formed on thesubstrate. That is, for example, it is the first magnetic layer, thesecond magnetic layer, anti-ferromagnetic layer, non-magnetic metallayer, or a crystal orientation layer. The non-magnetic metal layer, andthe crystal orientation layer are described hereafter. It is morepreferable that the conductive layer for the current is selected fromconductive layers being nearer the substrate in order to realize an aimof the present invention. In case of using both a crystal orientationlayer and a non-magnetic metal layer, for example, both layers areemployed as conductive layers for a controller.

[0051] The other mode of this invention is a magnetic head wherein atleast one layer selected from a group a crystal orientation layer and anon-magnetic metal layer is formed between said multi-layer and saidsubstrate. And the other mode of this invention is a magnetic head,wherein a non-magnetic metal layer is formed on said multi-layer.

[0052] Embodiment 1

[0053] As shown in FIG. 1, layers of a non-magnetic metal layer 12, amagnetic layer 13, an insulating layer 14, a magnetic layer 15, and ananti-ferromagnetic layer 16 are formed on a substrate 11 in the order.The non-magnetic metal layer 12 is formed of Zr of thickness 20 nm, themagnetic layers 13 and 15 formed of a layer having a thickness of 5 nmand made from an Ni-20 at %Fe alloy, and the insulating layer 14 ofoxide of Al of thickness 1.3 nm. The anti-ferromagnetic layer 16 isformed of a layer having a thickness of 10 nm and made from an Mn-22 at%Ir alloy. A voltage is applied between the non-magnetic metal layer 12and the anti-ferromagnetic layer 16 from a power supply 18. That is, apotential difference is generated in the magnetic layers 13 and 15 onboth ends of the insulating layer 14. A current tunnels through theinsulating layer 14 due to the potential difference. The tunnel currentis detected by a signal detector 19.

[0054] When the directions of magnetization of the magnetic layers 13and 15 are parallel, the maximum tunnel current flows, and when thedirections of magnetization of the magnetic layers 13 and 15 arecounter-parallel, the minimum tunnel current flows. In the presentembodiment, an applied voltage is 0.05 V. While in the presentembodiment, the power supply 18 is connected to the anti-ferromagneticlayer 16 and the non-magnetic metal layer 12, it is to be noted thatsince a potential difference will suffice to occur between the magneticlayers 13 and 15, the power supply 18 can be connected to the magneticlayers 13 and 15 directly. A current can be flown in the non-magneticmetal layer 12 by the power supply 17. A current causes to flow in thenon-magnetic metal layer 12 to thereby generate an induction magneticfield, and a magnetic field can be applied to the magnetic layer 13adjacent to the nonmagnetic metal layer 12. The magnitude of themagnetic field is in proportion to a current amount.

[0055]FIGS. 2A to 2C are schematic views of a multi-layer as viewed fromtop. As shown in FIG. 2A, a direction 22 of magnetization of a magneticlayer 15 of a multi-layer 21 is fixed to a direction in the figure. Thisis because the anti-ferromagnetic layer 16 is in contact with themagnetic layer 15. The direction 22 of magnetization of the magneticlayer 15 is parallel or counter-parallel with a detecting direction 24of an external magnetic field. When a current does not flow in thenon-magnetic metal layer 12, a direction 23 of magnetization of themagnetic layer 13 in FIG. 1 is directed at a direction as in FIG. 2. Thedirection 23 of magnetization is determined according to a leakagemagnetic field from the magnetic layer 15 and magnetic anisotropy of themagnetic layer 13 in FIG. 1. The direction 23 of magnetization is not atright angles to the detecting direction 24 of an external magneticfield.

[0056] As shown in FIG. 2B, a current causes to flow in the non-magneticmetal layer 12 by a power supply 17. The current is 5 μA. As a result,an induction magnetic field is applied to the magnetic layer 13, and adirection of magnetization of the magnetic layer 13 is directed as shownin the figure. The direction 25 of magnetization is substantially atright angles to the detecting direction 24 of the external magneticfield. This is because the induction magnetic field is offset bymagnetic fields other than the induction magnetic field applied to themagnetic layer 13.

[0057] Further, as shown in FIG. 2C, a magnetic recording medium 28causes to move closer to the magneto-resistive element. A magnetic fieldis applied to the magnetic layer 13 in FIG. 1 by a leakage magneticfield from the magnetic recording medium 28. When the leakage magneticfield from the magnetic recording medium is directed upward, a direction26 of magnetization of the magnetic layer 13 is directed at a directionshown in FIG. 2C. On the other hand, when the leakage magnetic fieldfrom the magnetic recording medium is directed downward, a direction 27of magnetization of the magnetic layer 13 is directed at a directionshown in FIG. 2C.

[0058] A change of a tunnel current tunneling through the insulatinglayer 14 is schematically shown in FIG. 3. In the figure, when theleakage magnetic field from the magnetic recording medium is directedupward, a magnetic field having a positive value is applied to themulti-layer. When the leakage magnetic field from the magnetic recordingmedium is not applied to the magnetic layer 13 in FIG. 1, a value of thetunnel current is “31” in FIG. 3. Where the direction of magnetizationof the magnetic layer 13 is substantially at right angles to thedetecting direction 24 of the external magnetic field, “31” in FIG. 3 ispositioned substantially in the center in the range of a change of thetunnel current. Since the leakage magnetic field from the magneticrecording medium is directed downward, the direction of magnetization ofthe magnetic layer 13 is “27” shown in FIG. 2c, the tunnel currentlowers to assume a value of “32” in FIG. 3. This is because thedirection of magnetization of the magnetic layer 13 and the direction ofmagnetization of the magnetic layer 15 are close to counter-parallel.

[0059] Where the leakage magnetic field from the magnetic recordingmedium is directed upward and the height thereof is the same as that ofthe above-described downward direction case, the tunnel currentincreases to assume a value of 33 in FIG. 3. This is because thedirection of magnetization of the magnetic layer 13 and the direction ofmagnetization of the magnetic layer 15 are close to parallel. The changeamount from the tunnel current 31 is substantially the same in absolutevalue at “32” and “33”. This is because the direction of magnetizationof the magnetic layer 13 when a leakage magnetic field from the magneticrecording medium is not present is substantially at right angles to thedetecting direction 24 of the external magnetic field. Where a magneticfield from the magnetic recording medium in a different direction of thesame height is applied, when the absolute value of the change amountfrom the tunnel current is substantially the same, playback waveformsare substantially symmetrical. In other words, the symmetry of theplayback waveforms lowers unless the direction of magnetization of themagnetic layer 13 when the leakage magnetic field from the magneticrecording medium is not present is not at right angles to the detectingdirection 24 of the external magnetic field. In the magnetic recordingplayback apparatus, the symmetry of the playback waveforms comprises animportant problem, and preferably, non-symmetry of playback waveforms iswithin 5%.

[0060] Therefore, it is necessary to make the direction of magnetizationof the magnetic layer 13, when the leakage magnetic field from themagnetic recording medium is not present, substantially at right anglesto the detecting direction 24 of the external magnetic field.

[0061]FIGS. 4A to 4C show the symmetry of playback waveforms asdescribed above. When a magnetic field which varies with time as shownin FIG. 4A is applied to the magneto-resistive element of the presentinvention, a playback output thereof shows a waveform excellent insymmetry as shown in FIG. 4B. On the other hand, where a current causesnot to flow in the non-magnetic layer 12, and the direction ofmagnetization of the magnetic layer 13 is not controlled, the playbackwaveform is asymmetrical as shown in FIG. 4C.

[0062] While in the present embodiment, the direction of magnetizationof the magnetic layer 15 has been parallel or counter-parallel to thedirection of the external magnetic field, a slight deviation of angle isallowed unless the symmetry of playback waveforms gets out. Likewise,also with respect to the direction of magnetization of the magneticlayer 13, a slight deviation of angle is allowed unless the symmetry ofplayback waveforms gets out.

[0063] While in the present embodiment, Zr is used as a material for thenon-magnetic metal layer 12, other non-magnetic metals can be also used.Further, while an Ni—Fe based alloy is used as a material for a magneticlayer, other magnetic materials can be also used. As other materials fora magnetic layer, a metal material having a low coercive force ispreferable. While an Mn—Ir based alloy is used as a material for ananti-ferromagnetic layer, other conductive anti-ferromagnetic layermaterials may be used. The magneto-resistive element type head shown inthe present embodiment has no recording ability. Accordingly, forcarrying out recording and playback, it is necessary to combine it witha recording induction type magnetic head for use.

[0064] In the magneto-resistive element according to the presentembodiment, since the rate of change of magnetic resistance of amulti-layer is high, it is possible to apply a magneto-resistive elementtype head which is advantageous for playback of information on themagnetic recording medium recorded with high density. Themagneto-resistive type head is a typical example of an application of amagneto-resistive element. However, since the magneto-resistive elementof the present invention represents high playback output and excellentsymmetry of playback waveforms, it is also suitable as a magnetic fieldsensor. This magnetic field sensor can be used for a rotary encoder orthe like.

[0065] Embodiment 2

[0066] As a multi-layer having a function similar to Embodiment 1, amagneto-resistive element using a multi-layer shown in FIG. 5 is formed.As shown in FIG. 5, layers of a crystal orientation control layer 52, ananti-ferromagnetic layer 53, a magnetic layer 54, an insulating layer55, and a magnetic layer 56 are formed on a substrate 51 in the order.Cu having a thickness of 10 nm is used for the crystal orientationcontrol layer 52, a layer having a thickness of 10 nm and made from anMn-22 at %Ir alloy used for the anti-ferromagnetic layer 53, and a layerhaving a thickness of 5 nm and made from an Ni-20 at %Fe alloy used forthe magnetic layers 54 and 56, respectively. An oxide of Al of thickness1.3 nm is used for the insulating layer 55. A voltage is applied betweenthe crystal orientation control layer 52 and the magnetic layer 56 by apower supply 58. That is, a potential difference occurs between themagnetic layers 54 and 56 on both ends of the insulating layer 55. Acurrent tunneling through the insulating layer 55 is detected by asignal detector 59.

[0067] An applied voltage in the present embodiment is 0.05 V. In thepresent embodiment, the power supply 58 is connected to the crystalorientation control layer 52 and the magnetic layer 56, but a potentialdifference will suffice to occur between the magnetic layers 54 and 56,and the power supply 58 may be connected to the magnetic layers 54 and56 directly.

[0068] A part of the non-magnetic metal layer 12 in Embodiment 1 isborne by the crystal orientation control layer 52 and theanti-ferromagnetic layer 53. A current can be flown in the crystalorientation control layer 52 and the anti-ferromagnetic layer 53 by thepower supply 57. A current is flown in the crystal orientation controllayer 52 and the anti-ferromagnetic layer 53 whereby an inductionmagnetic field is generated to enable an application of a magnetic fieldto the magnetic layer 56. The height of the magnetic field is inproportion to a current amount. Accordingly, the direction ofmagnetization of the magnetic layer 56 can be controlled and made atright angles to the detecting direction of the external magnetic fieldby a current flowing in the crystal orientation control layer 52 and theanti-ferromagnetic layer 53.

[0069] While in the present embodiment, an Ni—Fe based alloy is used asa material for a magnetic layer, other magnetic materials can be alsoused. As the other materials for a magnetic layer, a metal materialhaving a low coercive force is preferable. While an Mn—Ir based alloy isused as a material for an anti-ferromagnetic layer, other conductiveanti-ferromagnetic layer materials may be used. For the crystalorientation control layer 52, a material having a face centered cubicconstruction of other metal systems may be used. The magneto-resistiveelement type head shown in the present embodiment has no recordingability. Accordingly, it is necessary for carrying out recording andplayback to use it in combination with a recording induction typemagnetic head.

[0070] Embodiment 3

[0071] As a multi-layer having a function similar to Embodiment 1, amagneto-resistive element using a multi-layer shown in FIG. 6 is formed.As shown in FIG. 6, layers of a non-magnetic metal layer 62, a magneticlayer 63, an insulating layer 64, and a magnetic layer 65 are formed ona substrate 61 in the order. Zr having a thickness of 20 nm is used forthe non-magnetic metal layer 62, a layer having a thickness of 5 nm andmade from an Ni-20 at %Fe alloy used for the magnetic layer 63, and alayer having a thickness of 8 nm and made from a Co-17 at %Pt alloy usedfor the magnetic layer 65, respectively.

[0072] A coercive force of the magnetic layer 65 is higher than that ofthe magnetic layer 63, and is substantially parallel or counter-parallelto the detecting direction of the external magnetic field. Accordingly,in the low magnetic field, the direction of magnetization of themagnetic layer 65 having a relatively high coercive force is notrotated. On the other hand, the direction of magnetization of themagnetic layer 63 having a relatively low coercive force is rotated bythe external magnetic field. An oxide of Al of thickness 1.3 nm is usedfor the insulating layer 64. A voltage is applied between thenonmagnetic metal layer 62 and the magnetic layer 65 by a power supply68. That is, a potential difference occurs between the magnetic layers63 and 65 on both ends of the insulating layer 64. A current tunnelingthrough the insulating layer 64 is detected by a signal detector 69. Anapplied voltage in the present embodiment is 0.05 V. A current can beflown in the non-magnetic metal layer 62 by a power supply 67. A currentis flown in the non-magnetic metal layer 62 whereby an inductionmagnetic field occurs, and a magnetic field can be applied to themagnetic layer 63. The height of the magnetic field is in proportion toa current amount. Accordingly, the direction of magnetization of themagnetic layer 63 can be controlled and made at right angles to thedetecting direction of the external magnetic field by a current flowingin the nonmagnetic metal layer 62.

[0073] While in the present embodiment, a material having a relativelylow coercive force is used for the magnetic layer 63, and a materialhaving a relatively high coercive force is used for the magnetic layer65. Even if a material having a relatively high coercive force is usedfor the magnetic layer 63, and a material having a relatively lowcoercive force is used for the magnetic layer 65, similar results can beobtained. In such a case as described, a current can be also flown inthe magnetic layer having a relatively high coercive force to generatean induction magnetic field without providing a nonmagnetic metal layer.

[0074] In the present embodiment, Zr was used as a material for thenon-magnetic metal layer 62, but other non-magnetic metals can be alsoused. An Ni—Fe based alloy is used as a material for a magnetic layerhaving a low coercive force, but other magnetic materials having a lowcoercive force can be also used. Further, a Co—Pt based alloy is used asa material for a magnetic layer having a high coercive force, but othermagnetic materials having a high coercive force can be also be used. AnMn—Ir based alloy is used as a material for an anti-ferromagnetic layer,but other conductive anti-ferromagnetic materials can be also used.

[0075] The magneto-resistive element type head shown in the presentembodiment has no recording ability similar to Embodiment 1.Accordingly, it is necessary for carrying out recording and playback touse it in combination with a recording induction type magnetic head.

[0076] Embdodiment 4

[0077] As the multi-layer having a function similar to Embodiment 1, amulti-layer having three magnetic layers and two insulating layers canbe also applied. FIG. 13 and FIG. 14 are sectional construction views ofa magneto-resistive element according to Embodiment.

[0078] In the present embodiment, a multi-layer is laminated on anon-magnetic metal layer in order of a first magnetic layer, aninsulating layer, a second magnetic layer, an insulating layer, and athird magnetic layer. In a relatively low external magnetic field, adirection of magnetization of the first magnetic layer and the thirdmagnetic layer is parallel or counter-parallel with the detectingdirection of the external magnetic field. To this end, a high coerciveforce material may be used for the first magnetic layer and the thirdmagnetic layer. Further, it is necessary that the direction ofmagnetization of the second magnetic layer is changed by the externalmagnetic field detected. To this end, a low coercive force material maybe used for the second magnetic layer. The direction of magnetization ofthe second magnetic layer when the external magnetic field is notpresent is directed at right angles to the detecting direction of theexternal magnetic field by the induction magnetic field generated bycausing a current to flow in the non-magnetic metal layer, similar toEmbodiment 1. A voltage is applied between the first magnetic layer andthe third magnetic layer, similar to Embodiment 1. As such a multi-layeras described, there can be mentioned, for example, in FIG. 13, Co—Pt (10nm):35/Al—O:16 (1.3 nm)/Ni—Fe:15 (10 nm)/Al—O:14 (1.3 nm)/Co—Pt:13 (10nm)/Zr:12 (10 nm).

[0079] Further, the construction of the multi-layer comprises Ni—Fe (10nm)/Al—O (1.3 nm)/Co—Pt (10 nm)/Al—O (1.3 nm)/Ni—Fe (10 nm)/Zr (10 nm),and in a relatively low external magnetic field, a direction ofmagnetization of the Co—Pt layer as the second magnetic layer isparallel or counter-parallel with the detecting direction of theexternal magnetic field. The magnetic layer magnetized and rotated bythe external magnetic field comprises the Ni—Fe layer as the firstmagnetic layer and the third magnetic layer. Accordingly, the directionof magnetization of the Ni—Fe layer when the external magnetic field isnot present is directed at right angles to the detecting direction ofthe external magnetic field by the induction magnetic field generated bycausing a current to flow in the Zr layer as the non-magnetic metallayer.

[0080] Another example of the multi-layer shown in FIG. 14 is asfollows: In a multi-layer having the construction of Mn—Ir:52′ (10nm)/Ni—Fe:53 (10 nm)/Al—O:35 (1.3 nm)/Ni—Fe:15 (10 nm)/Al—O:14 (1.3nm)/Ni—Fe:13 (10 nm)/Mn—Ir:53 (10 nm)/Cu:52 (10 nm), in a relatively lowexternal magnetic field, magnetization of the Ni—Fe layer as the firstmagnetic layer and the third magnetic layer is fixed by the Mn—Iranti-ferromagnetic layer, and the direction of magnetization of theNi—Fe layer as the second magnetic layer is changed by the externalmagnetic field detected. A current is caused to flow in the Cu layer andthe Mn—Ir layer as a crystal orientation control layer to generate aninduction magnetic field, and when the external magnetic field is notpresent, magnetization of the Ni—Fe layer as the second magnetic layeris directed at right angles to the detecting direction of the externalmagnetic field.

[0081] Embodiemnt 5

[0082] As shown in FIG. 10, layers of a hard magnetic layer 112, anon-magnetic metal layer 113, a soft magnetic layer 114, an insulatinglayer 115, a soft magnetic layer 116, and an anti-ferromagnetic layer117 are formed on a substrate 111 in the order. The non-magnetic metallayer 113 magnetically separates the hard magnetic layer 112 and thesoft magnetic layer 114. A layer having a thickness of 5 nm and madefrom a Co-17 at %Pt alloy is used for the hard magnetic layer 112, Zr ofthickness 10 nm used for the non-magnetic metal layer 113, a layerhaving a thickness of 5 nm and made from an Ni-20 at %Fe alloy used forthe soft magnetic layers 114 and 116, and an oxide of Al of thickness1.3 nm used for the insulating layer 115, respectively. A layer having athickness of 10 nm and made from an Mn-22 at %Ir alloy is used for theanti-ferromagnetic layer 117. A voltage is applied between the hardmagnetic layer 112 and the anti-ferromagnetic layer 117 by a powersupply 118. That is, a potential difference occurs between the softmagnetic layers 114 and 116 on both ends of the insulating layer 115. Acurrent tunnels through the insulating layer 115 due to the potentialdifference. A tunnel current is detected by a signal detector 119. Whena direction of magnetization of the soft magnetic layers 114 and 116 isparallel, the maximum tunnel current flows, and when a direction ofmagnetization of the soft magnetic layers 114 and 116 iscounter-parallel, the minimum tunnel current flows.

[0083] In the present embodiment, an applied voltage is 0.05 V. In thepresent embodiment, the power supply 118 is connected to theanti-ferromagnetic layer 117 and the hard magnetic layer 112, but apotential difference will suffice to occur between the soft magneticlayers 114 and 116. The power supply 118 may be connected directly tothe soft magnetic layers 114 and 116. Further, a magnetic field isgenerated from the hard magnetic layer 112, and a magnetic field can beapplied to the soft magnetic layer 114.

[0084]FIG. 11A to 11C are schematic views of a multi-layer as viewedfrom top. A direction 122 of magnetization of the soft magnetic layer116 in the multi-layer 121 is fixed to the direction as shown in thefigure. This is because the anti-ferromagnetic layer 117 is in contactwith the soft magnetic layer 116, as sown in FIG. 10. A direction 122 ofmagnetization of the soft magnetic layer 116 is parallel orcounter-parallel with a detecting direction 124 of an external magneticfield. When the hard magnetic layer 112 is not magnetized, and the hardmagnetic layer 112 is demagnetized, a unidirectional magnetic field isnot generated from the hard magnetic layer 112. At this time, adirection 123 of magnetization of the soft magnetic layer 114 in FIG. 10is directed at the direction shown in FIG. 11. The direction 123 ofmagnetization is determined according to a leakage magnetic field fromthe soft magnetic layer 116 and a magnetic anisotropy of the softmagnetic layer 114. This direction 123 of magnetization is not at rightangles to the detecting direction 124 of the external magnetic field.

[0085] On the other hand, when the hard magnetic layer 112 ismagnetized, a unidirectional magnetic field is generated from the hardmagnetic layer 112. This magnetic field is offset by a magnetic fieldleaking from the soft magnetic layer 116. At this time, a direction 125of magnetization of the soft magnetic layer 114 is directed as shown inFIG. 11. The direction 125 of magnetization is substantially at rightangles to the detecting direction 124 of the external magnetic field.This is because a leakage magnetic field from other magnetic layersapplied to the soft magnetic layer 114 is offset.

[0086] Further, as shown in FIG. 11C, a magnetic recording medium 128 ismoved closer. A magnetic field is applied to the soft magnetic layer 114in FIG. 10 by a leakage magnetic field from the magnetic recordingmedium 128. When the leakage magnetic field from the magnetic recordingmedium is directed upward, a direction 126 of magnetization of the softmagnetic layer 114 is directed in a direction shown in FIG. 11C.Further, when the leakage magnetic field from the magnetic recordingmedium is directed downward, a direction 127 of magnetization of thesoft magnetic layer 114 is directed in a direction shown in FIG. 11C.

[0087] A change of current tunneling through the insulating layer 115 atthat time is shown schematically in FIG. 12. In the figure, when aleakage magnetic field from the magnetic recording medium is directedupward, a magnetic field of positive value is applied to a multi-layer.When the leakage magnetic field from the magnetic recording medium isnot applied to the soft magnetic layer 114 in FIG. 10, the value oftunnel current is “131” in FIG. 12. Where the direction of magnetizationof the soft magnetic layer 114 is substantially at right angles to thedetecting direction 124 of the external magnetic field, “131” in FIG. 12is positioned substantially in the center in the range of the change ofthe tunnel current.

[0088] When the leakage magnetic field from the magnetic recordingmedium is directed downward, a direction 127 of magnetization of thesoft magnetic layer 114 is as shown in FIG. 11, and therefore, a tunnelcurrent lowers to assume “132” in FIG. 12. This is because the directionof magnetization of the soft magnetic layer 114 and the direction ofmagnetization of the soft magnetic layer 116 approach counter-parallel.

[0089] Where the leakage magnetic field from the magnetic recordingmedium is directed upward, and the height thereof is the same as that ofthe above-described downward direction case, the direction 126 ofmagnetization of the soft magnetic layer 114 is as shown in FIG. 11, andtherefore, a tunnel current increases to assume “133” in FIG. 12. Thisis because the direction of magnetization of the soft magnetic layer 114and the direction of magnetization of the soft magnetic layer 116approach parallel.

[0090] Change amounts from the tunnel current 131 are “132” and “133”,absolute values of which are substantially the same. This is because thedirection of magnetization of the soft magnetic layer 114 when a leakagemagnetic field from the magnetic recording medium is not present issubstantially at right angles to the detecting direction 124 of theexternal magnetic field. Where a magnetic field from the magneticrecording medium which are the same height and different in direction isapplied, playback waveforms are substantially symmetrical when theabsolute value of the change amount from the tunnel current 131 issubstantially the same. In other words, unless the direction ofmagnetization of the soft magnetic layer 114 when the leakage magneticfield from the magnetic recording medium is not present is at rightangles to the detecting direction 124 of the external magnetic field,the symmetry of playback waveforms lowers. In the magnetic recordingplayback apparatus, the symmetry of playback waveform comprises animportant problem, and preferably, an asymmetry of playback waveforms iswithin 5%. To this end, it is necessary that the direction ofmagnetization of the soft magnetic layer 114 when the leakage magneticfield from the magnetic recording medium is not present is substantiallyat right angles to the detecting direction 124 of the external magneticfield.

[0091] While in the present embodiment, a Co—Pt based alloy is used as amaterial for the hard magnetic layer, other magnetic materials having ahigh coercive force can be also used. Further, Zr is used as a materialfor the nonmagnetic metal layer 113, but other non-magnetic metals canbe also used. Further, an Ni—Fe based alloy is used as a material forthe soft magnetic layer, but other soft magnetic materials can be alsoused. As a material for the anti-ferromagnetic layer, an Mn—Ir basedalloy is used. Other conductive anti-ferromagnetic materials can be alsoused. The magneto-resistive element type head shown in the presentembodiment has no recording ability. Accordingly, it is necessary forcarrying out recording and playback to use it in combination with therecording induction type magnetic head.

[0092] Embodiment 6

[0093] A magnetic disk device was prepared using the magneto-resistivetype head mentioned in Embodiment 1. A plan view of the magnetic diskdevice and a sectional view taken on line AA′ are shown in FIGS. 7A and7B, respectively. For a magnetic recording medium 71 rotated by amagnetic recording medium driving force 72, a material comprising aCo—Cr based alloy is used. Track width of a magnetic head 73 held by themagnetic head driving force 74 is 1 μm. In the figure, numeral 75designates a recording and playback processing system.

[0094] In the magnetic recording and playback apparatus using themagneto-resistive type head of the present invention, a high outputplayback signal was observed. An asymmetry of playback waveforms wasabout 2%. This is because magnetization of a magnetic layer magnetizedand rotated by a leakage magnetic field from the magnetic recordingmedium is substantially perpendicular to the magnetic field applyingdirection when a magnetic field from the magnetic recording medium isnot applied. In order that magnetization of the magnetic layer is madesubstantially perpendicular to the magnetic field applying direction, acurrent amount flowing in a non-magnetic metal layer may be controlled,and magnetization of the magnetic layer can be made substantiallyperpendicular to the magnetic field applying direction by a simplecircuit. If the current amount flowing in the non-magnetic metal layeris controlled according to the characteristic of a magneto-resistiveelement in each magnetic recording and playback apparatus, it ispossible to easily obtain a magnetic recording and playback apparatuswhich is excellent in symmetry of playback waveforms.

[0095] While in the present embodiment, the multi-layer mentioned inEmbodiment 1 was used, even the magneto-resistive type heads using themulti-layer described in Embodiments 2 to 5, the similar result wasobtained.

[0096] Embodiment 7

[0097] A magnetic memory was prepared using the magneto-resistiveelement according to the present invention mentioned in Embodiment 3.That is, the multi-layer shown in FIG. 6 was used. As mentioned inEmbodiment 3, in FIG. 6, the direction of magnetization of the magneticlayer 65 having a relatively high coercive force is not rotated in thelow magnetic field. On the other hand, the direction of magnetization ofthe magnetic layer 63 having a relatively low coercive force is rotatedby the external magnetic field. A direction of magnetization when nocurrent flows in the non-magnetic metal layer 62 is shown in FIG. 8A. Asshown in the figure, a direction 82 of magnetization of a magnetic layerhaving a relatively high coercive force in a multi-layer 81 is fixed.The direction 82 of magnetization is parallel or counter-parallel withthe direction 83 of an external magnetic field applied when informationof the magnetic memory is read.

[0098] As shown, a direction 84 of magnetization of a magnetic layerhaving a relatively low coercive force is not at right angles to thedirection 82 of magnetization of the magnetic layer having a relativelyhigh coercive force. This is because a leakage magnetic field from themagnetic layer having a relatively high coercive force is applied to themagnetic layer having a relatively low coercive force. With respect to arelation of the direction of magnetization shown in FIG. 8A, even if anexternal magnetic field is applied when information of the magneticmemory is read, the symmetry of waveforms read is poor, similar to thecase of the aforementioned magneto-resistive type head.

[0099] On the other hand, when, as shown in FIG. 8B, an inductionmagnetic field is generated by flowing current in a non-magnetic metallayer 62 by a power supply 67 and a magnetic field is applied to amulti-layer 81, a direction 85 of magnetization of a magnetic layerhaving a relatively low coercive force is directed in a direction shown.This is at right angles to the direction 82 of magnetization of amagnetic layer having a relatively high coercive force. With respect toa relation of the direction of magnetization shown in FIG. 8B, where anexternal magnetic field is applied when information of the magneticmemory is read, the symmetry of waveforms read is good, similar to thecase of the aforementioned magneto-resistive type head.

[0100]FIG. 9 is a schematic view for explaining the schematicconstruction of a magnetic memory according to one embodiment of thepresent invention. As shown in FIG. 8C, a magnetic field is applied to amulti-layer by a pair of magnetic field generating mechanisms 86. Byapplying the magnetic field, when a direction 87 of magnetization of amagnetic layer having a relatively low coercive force is directed asshown, a current tunneling through an insulating layer increases, andwhen a direction 88 of magnetization of a magnetic layer having arelatively low coercive force is directed as shown, a current tunnelingthrough an insulating layer reduces, then it is understood that thedirection 82 of magnetization of a magnetic layer having a relativelyhigh coercive force is directed as shown. On the other hand, by applyingthe magnetic field, when the direction 87 of magnetization of a magneticlayer having a relatively low coercive force is directed as shown, acurrent tunneling through an insulating layer reduces, and when thedirection 88 of magnetization of a magnetic layer having a relativelylow coercive force is directed as shown, a current tunneling through aninsulating layer reduces, then it is understood that the direction 82 ofmagnetization of a magnetic layer having a relatively high coerciveforce is directed opposite to that as shown.

[0101] As described above, if, when a magnetic field is applied to amulti-layer by the pair of magnetic field generating mechanisms 86, acurrent tunneling through the insulating layer is measured, thedirection of magnetization of a magnetic layer having a relatively highcoercive force is found. Accordingly, if the direction of magnetizationof a magnetic layer having a relatively high coercive force is arecording medium, it can be used as a magnetic memory.

[0102] Recording was carried out, as shown in FIG. 9, by causing acurrent to flow in a non-magnetic metal layer 62 below a multi-layer 81and a non-magnetic metal layer 91 above the multi-layer 81 to therebygenerate a magnetic field, and changing a direction of a magnetic layerhaving a relatively high coercive force. That is, in the playback, thisis utilized also when recording the non-magnetic metal layer 62 forcausing a current to flow in order to control the direction of amagnetic layer having a relatively low coercive force. Likewise, in theplayback, this is utilized also when recording a non-magnetic metallayer 91 for making use it as a conductor for measuring a currenttunneling through an insulating layer. A recording current is controlledby current application and measuring systems 94, 95, 96 and 97. Where acoercive force of a magnetic layer is high and a recording current isshort, it is effective that a multi-layer is heated, and the coerciveforce of the magnetic layer is lowered. For heating, preferably, thereis employed a method for drawing a laser beam by an optical system toirradiate it against the multi-layer.

[0103] In the playback, the non-magnetic metal layer 62 for connectingbetween the current application and measuring systems 94 and 96 or thenon-magnetic metal layer 91 for connecting between the currentapplication and measuring systems 95 and 97 is selected, and a currenttunneling through the insulating layer in a multi-layer at a point ofintersection therebetween is measured. As described above, a magneticfield is applied to the multi-layer by the pair of magnetic fieldgenerating mechanisms 86 in the measurement.

[0104] While in the present invention, the magneto-resistive elementmentioned in Embodiment 3 is used, even if the magneto-resistiveelements mentioned in Embodiments 1, 2 or 4 are used, a magnetic memorydevice can be likewise constituted.

[0105] For better understanding of the accompanying drawings,description of various reference numerals will be listed as follows:

[0106]11, 51, 61, 111 . . . substrate, 12, 62, 91, 113 . . .non-magnetic metal layer, 13, 15, 54, 56, 63, 65 . . . magnetic layer,14, 55, 65, 115 . . . insulating layer, 16, 53, 117 . . .anti-ferromagnetic layer, 52 . . . crystal orientation control layer,17, 18, 57, 58, 67, 68, 118 power supply, 19, 59, 69, 119 . . . signaldetector, 21, 81, 121 . . . multi-layer, 22, 82, 122 . . . direction ofmagnetization (of a magnetic layer with magnetization fixed), 23, 84,123 . . . direction of magnetization (when an external magnetic field ofa magnetic layer magnetized and rotated is not present), 24, 124 . . .detecting direction of external magnetic field, 25, 85, 125 . . .direction of magnetization (when an induction magnetic field of amagnetic layer magnetized and rotated), 26, 27, 87, 88, 126, 127 . . .direction of magnetization (when an external magnetic field of amagnetic layer magnetized and rotated is present), 28, 71, 128 . . .magnetic recording medium, 72 . . . magnetic recording medium drivingforce, 73 . . . magnetic head, 74 . . . magnetic head driving force, 75. . . recording and playback signal processing system, 83 . . .direction of external magnetic field, 86 . . . magnetic field generatingmechanism, 94, 95, 96, 97 . . . current applying and measuring system,112 . . . hard magnetic layer, 114, 116 . . . soft magnetic layer.

[0107] As described above, the basis of the present invention lies inthat a multi-layer having two or three magnetic layers separated by aninsulating layer is used, an induction magnetic field is applied to amagnetic layer in which magnetization is rotated by an external magneticfield, and the induction magnetic field applied to the magnetic field isoffset by a leakage magnetic field from the magnetic layer in whichmagnetization is fixed whereby magnetization of the magnetic layer issubstantially perpendicular to the magnetic field applying direction.Accordingly, a magneto-resistive element excellent in symmetry ofplayback waveforms was obtained. Further, a magnetic head, a magneticrecording and playback apparatus and a magnetic memory, which areexcellent in symmetry of playback waveforms could be obtained by themagneto-resistive element.

What is claimed is:
 1. A magnetic head having a magneto-resistiveelement, said magneto-resistive element comprising: a substrate, amulti-layer having at least a first magnetic layer, an insulating layer,and a second magnetic layer laminated on said substrate, a voltagesupplier applying a voltage between the first magnetic layer and thesecond magnetic layer; a direction of magnetization of one magneticlayer selected from a group of the first and the second magnetic layersbeing substantially parallel or counter-parallel with a detectingdirection of an external magnetic field; a direction of magnetization ofthe other magnetic layer, which is not substantially parallel orcounter-parallel with the detecting direction of the external magneticfield, being changeable by said external magnetic field, a controllerbeing a controller causing a current to flow in at least one conductivelayer selected from a group of layers laminated on said substrate in adirection crossing a laminating direction of said multi-layer andperpendicular to the external magnetic field; the controller being formaking a direction of magnetization of the other magnetic layer, whichis changeable by said external magnetic field, substantiallyperpendicular to the detecting direction of the external magnetic fieldwhen the external magnetic field is not present, and a detectordetecting, when the direction of magnetization of the other magneticlayer is changed by the external magnetic field, a change of currenttunneling through the insulating layer caused thereby.
 2. A magnetichead having a magneto-resistive element, said magneto-resistive elementcomprising: a substrate, a multi-layer having at least a first magneticlayer, an insulating layer, and a second magnetic layer laminated onsaid substrate, a anti-ferromagnetic layer being formed on lower orupper of said multi-layer, a voltage supplier applying a voltage betweenthe first magnetic layer and the second magnetic layer; a direction ofmagnetization of one magnetic layer selected from a group of the firstand the second magnetic layers being substantially parallel orcounter-parallel with a detecting direction of an external magneticfield; a direction of magnetization of the other magnetic layer, whichis not substantially parallel or counter-parallel with the detectingdirection of the external magnetic field, being changeable by saidexternal magnetic field, a controller being a controller causing acurrent to flow in at least one conductive layer selected from a groupof layers laminated on said substrate in a direction crossing alaminating direction of said multi-layer and perpendicular to theexternal magnetic field; the controller being for making a direction ofmagnetization of the other magnetic layer, which is changeable by saidexternal magnetic field, substantially perpendicular to the detectingdirection of the external magnetic field when the external magneticfield is not present, and a detector detecting, when the direction ofmagnetization of the other magnetic layer is changed by the externalmagnetic field, a change of current tunneling through the insulatinglayer caused thereby.
 3. A magnetic head according to claim 2, whereinsaid anti-ferromagnetic layer is formed on said substrate, and saidmulti-layer is formed on said anti-ferromagnetic layer.
 4. A magnetichead according to claim 2, wherein said multi-layer is formed on saidsubstrate, and said anti-ferromagnetic layer is formed on saidmulti-layer.
 5. A magnetic head having a magneto-resistive element, saidmagneto-resistive element comprising: a substrate, a multi-layer havingat least a first magnetic layer, an insulating layer, and a secondmagnetic layer laminated on said substrate, coercive force of onemagnetic layer selected from a group of the first magnetic layer and thesecond magnetic layer being higher than coercive force of the othermagnetic layer selected from the group of the first magnetic layer andthe second magnetic layer, a voltage supplier applying a voltage betweenthe first magnetic layer and the second magnetic layer; a direction ofmagnetization of one magnetic layer selected from a group of the firstand the second magnetic layers being substantially parallel orcounter-parallel with a detecting direction of an external magneticfield; a direction of magnetization of the other magnetic layer, whichis not substantially parallel or counter-parallel with the detectingdirection of the external magnetic field, being changeable by saidexternal magnetic field, a controller being a controller causing acurrent to flow in at least one conductive layer selected from a groupof layers laminated on said substrate in a direction crossing alaminating direction of said multi-layer and perpendicular to theexternal magnetic field; the controller being for making a direction ofmagnetization of the other magnetic layer, which is changeable by saidexternal magnetic field, substantially perpendicular to the detectingdirection of the external magnetic field when the external magneticfield is not present, and a detector detecting, when the direction ofmagnetization of the other magnetic layer is changed by the externalmagnetic field, a change of current tunneling through the insulatinglayer caused thereby.
 6. A magnetic head according to claim 5, wherein amagnetic layer having higher coercive force is in side of saidsubstrate.
 7. A magnetic head according to claim 5, wherein a magneticlayer having higher coercive force is in upper of said multi-layer.
 8. Amagnetic head according to claim 1, wherein at least one layer selectedfrom a group a crystal orientation layer and a non-magnetic metal layeris formed between said multi-layer and said substrate.
 9. A magnetichead according to claim 3, wherein at least one layer selected from agroup a crystal orientation layer and a non-magnetic metal layer isformed between said anti-ferromagnetic layer and said substrate.
 10. Amagnetic head according to claim 4, wherein at least one layer selectedfrom a group a crystal orientation layer and a non-magnetic metal layeris formed between said multi-layer and said substrate.
 11. A magnetichead according to claim 5, wherein at least one layer selected from agroup a crystal orientation layer and a non-magnetic metal layer isformed between said multi-layer and said substrate.
 12. A magnetic headaccording to claim 1, wherein a non-magnetic metal layer is formed onsaid multi-layer.
 13. A magnetic head according to claim 2, wherein anon-magnetic metal layer is formed on said multi-layer.
 14. A magnetichead according to claim 5, wherein a non-magnetic metal layer is formedon said multi-layer.
 15. A magnetic head according to claim 8, whereinsaid controller is a controller being a controller causing a current toflow in at least one conductive layer selected from a group of layerslaminated on said substrate in a direction crossing a laminatingdirection of said multi-layer and perpendicular to the detectingdirection of the external magnetic.
 16. A magnetic head according toclaim 9, wherein said controller is a controller being a controllercausing a current to flow in at least one conductive layer selected froma group of layers laminated on said substrate in a direction crossing alaminating direction of said multi-layer and perpendicular to thedetecting direction of the external magnetic.
 17. A magnetic headaccording to claim 10, wherein said controller is a controller being acontroller causing a current to flow in at least one conductive layerselected from a group of layers laminated on said substrate in adirection crossing a laminating direction of said multi-layer andperpendicular to the detecting direction of the external magnetic.
 18. Amagnetic head according to claim 11, wherein said controller is acontroller being a controller causing a current to flow in at least oneconductive layer selected from a group of layers laminated on saidsubstrate in a direction crossing a laminating direction of saidmulti-layer and perpendicular to the detecting direction of the externalmagnetic.
 19. A magnetic head having a magneto-resistive element, saidmagneto-resistive element comprising: a substrate, a multi-layer havinga first magnetic layer, a first insulating layer, a second magneticlayer, a second insulating layer, and a third magnetic layer laminatedon said substrate in said order, a voltage supplier applying a voltagebetween the first magnetic layer and the third magnetic layer; adirection of magnetization of one magnetic layer of a set of the firstand third magnetic layers and the second magnetic layer beingsubstantially parallel or counter-parallel with a detecting direction ofan external magnetic field; and a controller making a direction ofmagnetization of the other magnetic layer of the set of the first andthird magnetic layers and the second magnetic layer substantiallyperpendicular to the detecting direction of an external magnetic fieldwhen the external magnetic field is not present; and a detectordetecting, when the direction of magnetization of the other magneticlayer is changed by the external magnetic field, a change of a currenttunneling through the insulating layer caused thereby.
 20. The magnetichead according to claim 19, wherein coercive force of said one magneticlayer is higher than that of the other magnetic layer, and saidcontroller is a controller causing a current to flow in a non-magneticmetal layer laminated on said multi-layer and in an inner direction of alayer surface of said non-magnetic metal layer.
 21. The magnetic headaccording to claim 19, wherein said element has anti-ferromagneticlayers on both sides of said multi-layer, said set of first and thirdmagnetic layers constituting said one magnetic layer, and saidcontroller is a controller causing a current to flow in a crystalorientation control layer laminated on the side opposite to the side inwhich said multi-layer of one of said anti-ferromagnetic layers isformed, and parallel to a layer surface of at least one layer of saidanti-ferromagnetic layers and said crystal orientation control layer.22. A magnetic head having a magneto-resistive element, saidmagneto-resistive element comprising: a substrate, a multi-layer havinga hard magnetic layer, a nonmagnetic metal layer, a first soft magneticlayer, an insulating layer, a second soft magnetic layer, and ananti-ferromagnetic layer laminated on said substrate in said order fromthe side closer to said substrate, a voltage supplier applying a voltagebetween the first soft magnetic layer and the second magnetic layer, theanti-ferromagnetic layer and the second soft magnetic layer beingsubjected to magnetic exchange coupling, a direction of magnetization ofthe second soft magnetic layer being substantially parallel orcounter-parallel with a detecting direction of an external magneticfield due to the exchange coupling, and a means for making a directionof magnetization of the first soft magnetic layer substantially at rightangles to the detecting direction of the external magnetic field due tothe hard magnetic layer when the external magnetic field is not present,and detecting, when the direction of magnetization of the first softmagnetic layer is changed by the external magnetic field, a change of acurrent tunneling through the insulating layer caused thereby.
 23. Amagnetic head comprising: a magneto-resistive type head for read and aninduction type head for write, said magneto-resistive type head havingthe magneto-resistive element described in any one of claims
 1. 24. Amagnetic recording apparatus comprising: a magnetic recording medium, amagnetic head provided corresponding to a recording surface of themagnetic recording medium, a driving unit for the magnetic recordingmedium, a driving unit for the magnetic head, and a recording andplayback signal processing system, said magnetic head comprising themagnetic head of claim
 23. 25. A magnetic memory comprising: amagneto-resistive element set forth in claims 1; and a magnetic fieldgenerating mechanism for directing a direction of magnetization of saidone magnetic layer of the magneto-resistive element at the desireddirection.
 26. The magnetic memory of claim 25, wherein said memory isprovided with a means for heating said magneto-resistive element.